Well my group leak is back in my LP Pro stradivari. As she warms up to a pressure of about 0.4 bars out flows the water. The group gaskets are about six months old now at most so I can't imagine them needing another replacement so soon. I grind to make sure I don't need gorilla pulls on the lever. The leak is coming direct from the dispersion screen and requires that I empty my drip tray after warm up and before shot pulling. Anyone have a clue what could be causing this? I wonder if I need a new piston sleeve. Any help appreciated. And the shots I am pulling lately are tasty as always so it isn't at least effecting that.

What makes you think you don't need new seals? My go about every six months and I use the machine once a day. Once in a blue moon I'll use it twice in a day.

I've found using vinegar really hard on the seals. I used to use that to descale but find actual descaler does a better job.

mayhew wrote:What makes you think you don't need new seals? My go about every six months and I use the machine once a day. Once in a blue moon I'll use it twice in a day.

Yep, six months in and I have water trickling from the grouphead. I pull 2-3 a day though. I'll just swap heads though, as I have a spare one ready to go - it makes my life easier and saves me from having to go downtown to get a spro or cap.

I'd suggest you change the seals, even if you don't think you need to.

6 months? Sounds like planned obsolescence! If the cylinder walls (liner in this case) are not covered with black rubber gunk (and the cylinder walls have been lubricated somewhat regularly to prevent this type of wear) then in all likelihood the water is creeping around the back side of the top seal in the piston groove itself. I think this is more of a problem with the plastic piston than the brass since the plastic one does not really expand on heating and the plastic as well has a kind of rough surface texture which would come into play with the behind the seal leak.
If the seal is flexible and not torn and there is no black stuff on the cylinder walls you can solve this by, yes, installing new seals, but you can also use a trick. Take out the piston and put it into a cup or real hot water and remove the top seal using a pick or probe (don't tear it). Give the piston a couple of wraps of teflon tape in the groove, nice and smooth and tight, put some Dow 111 all over the back of the seal and spread a little in the groove. Install the seal and dollars to donuts it will not leak on heat up anymore.
We have 2 years on our current set of Faema seals....I lube the group about once every two months.....but 6 months on a set of seals seems a bit short.

orphanespresso wrote: Take out the piston and put it into a cup or real hot water and remove the top seal using a pick or probe (don't tear it). Give the piston a couple of wraps of teflon tape in the groove, nice and smooth and tight, put some Dow 111 all over the back of the seal and spread a little in the groove. Install the seal and dollars to donuts it will not leak on heat up anymore.
We have 2 years on our current set of Faema seals....I lube the group about once every two months.....but 6 months on a set of seals seems a bit short.

So, every 2 months you remove the seal and add more and more tape?

I just swapped the heads right after my last post, and removed the piston - low and behold, the top seal had folded a little in two spots. I don't think this just happened, and may have actually happened the last time I rebuilt that head.

Oh no, there is no tape on that piston.....commercial levers are built to be able to pull out the piston easily from the top and wipe out the cylinder, wipe off the piston and seals, relube everything and put back together...the maintenance angle is part of the design. I am just saying that you can fix the standing leak on heatup with some tape and lube....or even use a seal that does not quite fit right in a pinch with this method. The machines we have gotten from Italy are pretty much half teflon tape in composition.

When I descale the boiler I use citric acid, never vinegar. Darn I was hoping not to have to change the seals again, but I will of course. My last set of gaskets went an entire year without even hinting at a leak or showing any signs of wear after daily use pulling 4-8 doubles. First I will pull the group and see about cleaning up the nylon sleeve and check it for any damage. I ran out of the lube I was using so I will have to find more again.

6 months in-between seal changes seems absurd. The original seals on my Gaggia Factory are still working properly some 3.5 years after I bought the machine, but I'd drop the piston and re-lube the seals about once a quarter. Same story, less time on my Cremina as I just bought it in March. I use the heck out of it, pulling on average 4 doubles a day for the last 9 months.

FWIW, I descale and re-lube at the same time, never move the lever until up to operating temp, and never grind fine enough to require a monster pull (well above the 30# suggestion) to extract the shot.

remove the showerscreen and as the machine warms up
check if is leaking between grouphead and sleeve
or from sleeve and piston

Brilliant Stefano!